Many electronic images have an associated look-up table that describes pixel values found in an image. For example, a palettized color image may have an associated color palette table that describes the colors found in the image. Typically, this color table is 256 or 65,536 entries long and contains RGB (red, green, blue) values associated with the image pixels. The image pixels are associated with the RGB values via indices.
Watermarking of digital images provides a way for copyright enforcement and image authentication or verification. For example, watermarking may be used to detect changes in image data, thus verify whether a given image came from a trusted source.